This invention relates to a connector for electrically connecting an electric apparatus such as a relay or a timer to an external circuit through lead lines. In particular, this invention relates to such a connector having an attaching mechanism for detachably attaching to a rail.
FIG. 22 shows an example of prior art connector for an electric apparatus provided with an attaching mechanism comprising an elastic hook 2 and a latch 3 on the bottom surface of a housing 1 for attaching to a rail (not shown) by engaging to both of its edge parts such that a plurality of such connectors can be detachably attached in parallel to the rail. Because the elastic hook 2 protrudes downward from the housing 1, it is easily breakable if the connector is dropped accidentally and especially if the force of impact has a twisting effect. For this reason, it may be considered to make the housing 1 with a nylon resin material which is highly shock-resistant and to form the elastic hook 2 integrally with the housing 1, but nylon resins are easily deformable with temperature and it is difficult to obtain a desired level of electrical insulation characteristic.
It is therefore an object of this invention, in view of the problem with such a prior art connector, to provide an improved connector for an electric apparatus having a mechanism for attaching to a rail and not easily damaged when dropped.
A connector according to this invention, with which the above and other objects can be accomplished, may be characterized as comprising a case and a base to be engaged or integrally formed together and wherein the base has an elastic hook and a latch formed integrally on its bottom surface for engaging both edge parts of a rail so as to mount the connector removably to the rail, and wherein the case has extended members extending from its lower edge parts for covering both side surfaces of the elastic hook and thereby protecting the elastic hook from damage. With a connector thus structured, these extended members protect the elastic hook even if the connector is accidentally dropped such that the elastic hook is not easily damaged. In other words, the elastic hook need not be made of nylon resin or the like and hence the freedom in design is increased.
As an example of the embodiment of the invention, at least one protrusion may be provided on the bottom surface of the base between the extended members on the case and the elastic hook for limiting twisting deformation of the elastic hook. With such a protrusion or protrusions additionally provided, the damage to the elastic hook by a twisting deformation can be more effectively prevented. In particular in the case of a connector with a housing having the case and the base formed integrally and having an elastic hook and a latch molded integrally on the bottom surface for engaging edge parts of a rail, such extended members and protrusions can effectively control the effect of a twisting force and protect the elastic hook from being damaged.
As another example of the embodiment of the invention, an external side portion of the bottom surface of the elastic hook may be arcuately curved. Such an curved surface serves to distribute and relieve the effect of an impact force, say, when the connector is accidentally dropped, and the damage to the connector can be prevented even more effectively.
As still another example of the embodiment of the invention, an opening may be provided to the case through which the elastic hook can be operated upon. If the case has four side surfaces and two of these four side surfaces are extended to provide aforementioned extended members, such an opening may be formed in another side surface adjacent to those with an extended member. Such an opening may serve to allow a tool to pass therethrough for removing the rail attached to the connector from the elastic hook. This makes the work much easier for removing the attached rail.
It is preferable to form the aforementioned opening with edge parts such that the side surfaces of the elastic hook contact them when the case and the base are engaged together because this will prevent the elastic hook from being subjected to a twisting force and the elastic hook can be further dependably protected from the effect of a twisting force in a simple manner.
It is further preferable to provide the base with an indentation and an outward facing guide surface for guiding the aforementioned tool to the indentation for operating on the elastic hook and to position this outward facing guide surface so as to be visible through the opening. This makes it much easier to insert the tool into the opening so as to bring its tip into the indentation for operating on the elastic hook to release the connector from the rail.